Coated nitrocellulose powder and process of making the same



UNITED STATES PATENT OFFICE.

RICHARD G. WOODBRIDGE, JR, OF WILMINGTON, DELAWARE, ASSIGNOR TO E. I. nu

PONT DE NEMOURS & COMPANY, 0F OF DELAWARE.

WILMINGTON, DELAWARE, A. CORPORATION COATED NITROCELLULOSE POWDER ANDPROCESS OF MAKING THE SAME.

No Drawing.

To all whom it may concern: v

Be it known that I, RICHARD G. W001)- nnnion, J12, a citizen of theUnited States, and a resident of Wilmington, in the county of NewCastleand State of Delaware, have invented a certain new and usefulCoated Nitrocellulose Powder and Process of Making the Same, of whichthe following is a specification.

This invention relates to a propellent powder suitable for small armsand ordnance, and it comprises firstly, as a new article of manufacture,nitrocellulose powder grains having a firmly adherent coating of amaterial comprising an inorganic nitrate, and particularly an easilyignitible propellant, and, secondly, a process of producing the newpropellent powder.

Considerable variation not infrequently occurs in the ballistics ofapparently similar charges of smokeless powder. The most important ofthe factors responsible for this defect appears to be a lack ofuniformity in ignition.

The obj ct of my invention is to provide a nitrocell lose powdercharacterized by a marked improvement in ballistic qualities, andespecially in the ease and uniformity of ignition. I have discoveredthat a powder having the above-mentioned desirable qualities can beproduced by applying to the nitrocellulose grains, by means of certainbinding agents, an inorganic nitrate or an easily ignitible inorganicexplosive containing, for example, barium, or potassium, nitrate, andparticularly black powder, which contains charcoal and sulfur inaddition to potassium nitrate.

The substances that I have found most valuable as binding agents arethose which are non-volatile solvents for nitrocellulose, that is,substances which are capable, especially in their liquid state, ofcolloiding with the nitrocellulose of the powder grains to be treated. Alarge number of substances are suitable for this purpose, but the classof substances which I prefer are the nitrobenzenoid hydrocarbons, andespecially those which are themselves explosives, such as'dinitrotoluene.

The nitrocellulose powder grains to which a coating of theabove-described composi- Specification of Letters Patent.

Patented Oct. 5, 1920.

Application filerl February 20, 1920. Serial No. 360,194.

tion may be applied according to my inventron may be made according toany of the known processes of manufacture and may be of dlfierent sizesand shapes, such as are obtalned by pressing colloided nitrocellulosecomposition through dies, with or without pins to give perforations,into strings, and then granulating the strings; or as may be made byrolling the colloided nitrocellulose composition into sheets andgranulating'. Or the nitrocellulose powder grains used may be of theso-called bulk type, which are usually made by a process of manufacture.

in which grains of nitrocellulose composithe nitrocellulose is formedinto grains by being agitated in water with a suitable solvent. Or thenitrocellulose powder may be any kind of a mixture of grains obtained bysub-dividing nitrocellulose powder grains by any of several processes ofgrinding or sub-dividing.

The nitrocellulose vpowder grains to which my invention is applicablecan be made for example from a mixture of nitrocellulose solubleinether-alcohol (2 parts ether by weight to 1 part alcohol) withnitrocellulose relatively insoluble in ether-alcohol, or may be madefrom soluble nitrocellulose alone, and may contain, uniformlydistributed therethrough, a stabilizer such as diphenylamin, inorganicnitrates, graphite, powdered metals, nitro -compounds, deterrentmaterials, etc., in varying amounts.

My invention is described more in detail as follows 100 parts by weightof nitrocellulose powder grams are mixed in a revolving drum tion aresubjected to a partial hardening treatment by means of a solventmixture, or

first with about 2 parts of a nonvolatile solvent for nitrocellulose,such as dinitrotoluene, and then with from about 1 to 10 parts ofafinely pulverized black powder composition. The dinitrotoluene, whichfunctions as a deterrent as well as a binding agent, may be any one 'ofseveral isomers, or a mixture of the same obtained by the directnitration of toluene, but I prefer to use pure dinitrotoluene, i. 6.,1-2-4 dinitrotoluene. After the dinitrotoluene and nitrocellulose powdergrains have been thoroughly mixed, '5. e., in from 5 to 10 minutes, theblack powder is added. Heat is applied in any suitable manner totheoutside of the drum or to the jacket of the' usually suflicient,depending on the purity of the dinitrotoluene. At a temperature of aboutC. the dinitrotoluene melts and, being a solvent for nitrocellulose, itcolloids with the nitrocellulose on the surface of the powder grains andimpregnates the same to a substantial distance, while the black powdercomposition is in part firmly cemented to the surface of the powdergrains, forming an exterior coating, and is also in part at the sametime, and to a considerable extent, carried into the pores of thenitrocellulose colloid. In this manner the black powder composition isso firmly attached to the smokeless powder grains that it is essentiallyan integral part of the powder and cannot be completely removed withoutdestroying the powder grains.

Ido not limit myself to the use for every 100 parts of nitrocellulosepowder grains of about two parts dinitrotoluene and from about 1 to 10parts of black powder composition, as it is evident that the amount ofblack powder and dinitrotoluene would necessarily be varied according tothe ballistics desired. In place of dinitrotoluene I may useasnon-volatile solvents for nitrocellulose, other aromaticnitrohydrocarbons, and especially those which are deterrents, such asmononitronapthalene, or aromatic amids such as phenylacetanilid,dimethyldiphenylurea, etc., but in case of a non-volatile solvent suchas dimethyldiphenylurea with a relatively high melting point of 120 to121 0., when pure, I prefer to add to this 25% or more of dinitrotoluenein order to obtain a mixture with a melting point considerably below 100C.

Furthermore, while I prefer to use a nonvolatile solvent fornitrocellulose as a binding agent for the black powder composition inthe manner above described, I have found that other binding agents suchas diphenylamin, rosin, etc., may be used, which, while not solvents fornitrocellulose can be melted at a temperature which has no injuriouseffect on the stability of the powder. While diphenylamin and rosin arenot solvents for nitrocellulose and do not impregnate the surface of thepowder grains in the same manner as dinitrotoluene and other solventsfor nitrocellulose, they'are to a cer tain extent carried into the poresof the powder grains and thereby serve as a fairly satisfactory bindingagent to bind the black powder composition to the surface of thenitrocellulose grains. Both diphenylamin and rosin are strongerdeterrents than dinitrotoluene so that a given quantity of either of theformer will have more effect on the ballistics of the powder than alarger quantity of the latter.

' The black powder which I prefer to use is the kind generally used forblack sporting powder and has approximately the following composition: 74.0% saltpeter, 10.4% sulfur, 15.6% charcoal.

However, I do not limit myself to any particular composition or degreeof granulation of black powder as it is evident that I would use thatcomposition which by test gives the best results, and likewise thatgranulation which by tests is found most suitable for the particularpurposes desired. In general, I prefer to use black powder meal. Also, Ido not limit myself to the use of black powder or to the use of blackpowder containing saltpeter since I have found that many nitratemixtures, such as a mixture of barium and potassium nitrates, and manynitrates alone such as gotassium nitrate, can be applied to the powdergrains by my process so as to give improved ballistic qualities'to thepowder grains, as indicated by easier and more uniform ignition and bycleaner burning of the powder.

I claim:

1. The process of coating nitrocellulose powder grains with an easilyignitible inorganic explosive which comprises applying the latter tosaid grains in the presence of a non-volatile binding agent melt-able ata temperature which has no injurious effect on the stability of thepowder, while heating the above mentioned materials to a temperatureslightly above the melting point of the binding agent.

2. The process of coating nitrocellulose powder grains with an'easilyignitible inorganic explosive comprising a metal nitrate which comprisesapplying the latter to said grains in the presence of a non-volatilebinding agent meltable at a temperature which has no injurious effect onthe stability of the powder, while heating the above mentioned materialsto a temperature slightly above the melting point of the binding agent.

3. The process of coating nitrocellulose powder grains with black powderwhich comprises applying the latter to said grains in the presence of anon-volatile binding agent meltable at a temperature which has noinjurious eifect on the stability of the powder, while heating the abovementioned materials to a temperature slightly above the melting point ofthe binding agent.

l. The process of coating nitrocellulose powder grains with a blackpowder composition which comprises heating a mixture of said powdergrains, said black powder composition, and a non-volatile solvent fornitrocellulose at a temperature suflicient to melt said non-volatilesolvent and to cause the same to colloid with the nitrocellulose of thepowder grains.

5. The process of coating nitrocellulose powder grains with blackpowdercomposition by heating a mixture of said powder grains, black powdercomposition and dinitrotoluene-at a temperature sufficient to melt saiddinitrotoluene and to cause the same to colloid with thenitocellulose ofthe powder grains.

6. The process of coating nitrocellulose powder grains with black powdercomposition by heating a mixture of said powder grains, black powdercomposition and substantially pure 1-2-4 dinitrotoluene at a temperaturesufficient to melt said 1-2-4 dinitrotoluene and to cause the same tocolloid with the nitrocellulose of the powder grains.

7. The process of coating nitrocellulose powder grains with black powdercomposition by heating a mixture of said powder grains, black powdercomposition and a deterrent material, which is a non-volatile solventfor nitrocellulose, at a temperature "sufiicientto melt said deterrentmaterial and to cause the same to colloid with the nitrocellulose of thepowder grains.

8. The process of coating nitrocellulose powder grains with black powdercomposition by heating a mixture of said powder grains, black powdercomposition and a binding agent at a temperature suflicient to melt orsoften said binding agent.

9. lhe process of coating nitrocellulose powder grains with an inorganicnitrate which comprises heating a mixture of said powder grains, saidinorganic nitrate, and a binding agent at a to melt or soften saidbinding agent.

10. The process of coating nitrocellulose I powder grains with potassiumnitrate which comprises he ating a mixture of said powder grains, saidInorganic nitrate, and a binding agent at a temperature sufiicient tomelt or soften said binding agent.

comprising ni- 11. A propellent powder having a firmly trocellulosepowder grains adherent poating of an easily'ignitible in-' organicexplosive.

12. A propellent powder comprising nitrocellulose powder grains having afirmly adherent coating of an easily ignitible propellantcomprisingfpotassium nitrate.

13. A propellent powder comprising nitrocellulose powder grains having afirmly adherent coating of black powder.

14. A propellent powder comprising nitrocellulose powder grains and aneasily ignitible propellant held to said grains by a non-volatllelnnding agent meltable at a temperature that has no injurious effect 'onthe stability of the powder.

temperature sufiicient' 15. A propellent powder comprisingnitrocellulose powder grains and an easily ignitible propellant held tosaid grains by a non-volatile binding agent meltable at a temperaturethat has no injurious effect on the stability of the powder, andcapable, when melted, of dissolving nitrocellulose.

16. A propellent powder comprising nitrocellulose powder grains and aneasily ignitible inorganic explosive held to said grains by anon-volatile nitrocellulose-sol- .Vent which is itself an explosive.

cellulose powder grains andan inorganic nitrate held to said grains by adeterrent material which is a solvent for nitrocellulose.

20. A propellent powder comprising nitrocellulose powder grains and aninorganic nitrate held to said grains by dinitrotoluene. 21. Apropellent powder comprising nitrocellulose powder grains having acoating of black powderheld to the surface of the grains by an aromaticintro-hydrocarbon capable of colloiding with nitrocellulose.

22. A propellent powder comprising nitrocellulose powder grains having acoating of black powder held to the surface of the grains by anitrobenzenoid hydrocarbon;

23. A propellent powder comprising nitrocellulose powder grains havingblack powder firmly attached to the surface of said grains by adinitro-benzenoid hydrocarbon.

24:. propellent powder comprising nitrocellulose powder grains having asubstance comprising potassium nitrate firmly attached to the surface ofsaid grains by a dinitro-benzenoid hydrocarbon. i

25. A propellent powder comprising nitrocellulose powder gralns having asubstance comprising potassium nitrate firmly attached to the surface ofsaid grains by a dinitrotoluene.

held to the surface of said grains by a nonvolatile solvent fornitrocellulose.

28. A propellent powder comprising 100 parts of nitrocellulose powdergrains and from about 1 to 10 parts of black powder surface of saidgrains by subdilheld to the surface of said grains by about 2 parts ofa, non-volatile solvent for nitrocellulose.

29. A propellent powder comprising 100 parts of nitrocellulose powdergrains and from aboutl to 10 parts of black powder held to the vsurfaceof said grains by about 2 parts of dinitrotoluene.

30. A prop'ellent powder comprising 100 parts of nitrocellulose fromabout 1 to 10 parts of black powder held to the surface of said grainsby a deterrent material which is capable of co'l10iding withnitrocellulose.

4 in testimony whereof I affix my si nature. 15

RICHARD e. woonemneh, JR.

powder grains and 10

